SI unit of dose of radiation absorption?
**Core Concept**
The question is testing the student's knowledge of the unit used to measure the dose of radiation absorption in the human body. The correct unit is based on the International System of Units (SI) and is defined as the amount of radiation energy absorbed per unit mass of tissue.
**Why the Correct Answer is Right**
The correct unit of dose of radiation absorption is the Gray (Gy). It is defined as the absorption of one joule of radiation energy per kilogram of matter. This unit is widely used in medical physics and radiation therapy to measure the dose of radiation delivered to patients. The Gray is a direct measure of the energy absorbed by the tissue, taking into account the mass of the tissue.
**Why Each Wrong Option is Incorrect**
**Option A:** Sievert (Sv) - The Sievert is a unit of dose equivalent, which takes into account the biological effect of radiation on the human body. While it is related to radiation absorption, it is not a direct measure of the dose of radiation energy absorbed.
**Option B:** Rad - The Rad is an older unit of radiation absorbed dose, but it is not part of the SI system and has been largely replaced by the Gray.
**Option C:** Becquerel (Bq) - The Becquerel is a unit of radioactivity, measuring the number of nuclear decays per second. It is not a measure of radiation absorption or dose.
**Clinical Pearl / High-Yield Fact**
When working with radiation therapy, it is essential to understand the difference between absorbed dose (Gray) and dose equivalent (Sievert) to accurately assess the risk of radiation-induced injury to patients.
**Correct Answer:** C. Gray (Gy)